It's a mistake to think that as a beginner you don't need good gear and that the good gear is for advanced players. Quite the opposite. Especially at the beginning, when you are learning the crucial basics, bad gear can ruin you. Worst scenario: playing with bad gear is so awful that you stop playing altogether. Slightly better scenario: bad gear may make it difficult to learn some crucial skills or make you develop bad habits, that you later have to invest more time into to "relearn" or "unlearn", so in the end it slowed you down. An advanced player on the other hand can overcome limitations of bad gear and still make nice music (although likely he/she would prefer better gear and make even better music with it and enjoy it more).

As a beginner, you should not get cheap gear for the reason that you think "cheap is good enough for beginners". More valid reasons for cheap gear would be "not enough money for something better" or "not sure I'm gonna stick with it". But never use "beginner" as the sole reason to buy cheap. In the end it will be more expensive, because you will likely invest more later, and it will likely set back your learning.

With that background, the P45 (or comparable) is not overkill for a beginner, but the absolute minimum. Anything below (like semi weighed) will be detrimental to learning the piano. If you can, i.e. if none of the other reasons apply, you should even aim at least one step higher.

I can afford it (thankfully). As for "I'm gonna stick with it part" : an expression of doubt/fear makes it more likely that one won't, so I am not going for that line of thought :)

I completely agree with you on the idea that bad gear can ruin my piano experience completely. I had seen this @tennis when i bought an absolutely shitty racquet as a kid and didn't restart tennis until after 13 years from then.

Not sure what lies one step higher (?), but it seems like it meets my needs. Wasn't sure if there was something particularly lacking in this one? Would be great if you could expand on that. It seems like one could keep paying more for a better piano experience.

If you're talking about models, then the one up would be the Yamaha P105( older model) or the P115 (current model). They share the same type of keys as the p45, the only real difference appears to be the polyohony (how many notes can sound at the same time) which probably isn't a issue for the complexity of pieces you'd be learning to play at this stage.

I personally learnt to play on a P105 and thought it was fine. 3 years on I've recently just switched to a Roland HP605. You can always trade up later when you know you enjoy playing :)

You essentially control the volume of the notes you're playing (i.e. the dynamics) by how strong you hit the keys. Without weighted keys this will feel very different (or not be possible at all).

P45 is a pretty good for starters. I've been practising on a Yamaha P105 (which has a very similar keys afaik) for a bit more than three years now and while I want to upgrade to a better action at this point I can still make progress with the P105 - probably for quite some more time :)

Keep in mind that in some countries, if you buy online you can void the Yamaha Warranty. I also agree that if you are a beginner, getting the cheapest equipment is not the best idea. You don't want to go all out, but you need to buy at a happy medium.

Where are you placing it? If on a L-85 stand then you'll probably want the LP-5A pedal bar to go with it but that's not compatible with the P45, so in that case I suggest trying to get a P105, because it's from the previous generation (now replaced by the P115) you might be able to get it at almost the same price as the P45.